Packaging materials

ABSTRACT

In the packaging materials of the invention, a pair of inflation film layers is joined to each other by blocking in a flexible state to some degree without using adhesive. Therefore, they are not always joined completely integrally, and little space remains between the inflation film layers. The space can be increased by controlling the properties of the inflation film layers, blocking conditions and the like. By this pseudo-adhesion, physical strength such as tear strength is improved, buffer action is imparted, and curling is prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to packaging materials suitable for variousphotographic photosensitive materials, light-sensitive materials andelectronic parts, particularly for relatively heavy materials amongthem, such as a roll film for movie.

2. Description of the Prior Art

As a packaging material for photographic photosensitive materials, it isnecessary to have various properties including gas barrier,moistureproofness, antistatic property, rigidity, physical strength suchas breaking strength, tear strength, impact puncture strength, Gelbotest strength and wear resistance, heat sealing properties such as heatseal strength, cut-seal ability, hot tack properties (hot-seal ability)and seal ability of contrasting materials, flatness, slipping character,low dusting characteristics, and the like. Generally, it is difficult tosatisfy these properties by a single material. Therefore, the packagingmaterial is usually composed of two or more layers. As the packagingmaterial for rolls or sheets of photographic photosensitive materials,the inventor has already disclosed a packaging material of whichphysical strength is raised by combining two uniaxially stretched filmlayer (U.S. Pat. No. 4,331,725). Another packaging material suitable forheavy photosensitive materials is a triple layer laminated film composedof a foamed sheet and two uniaxially stretched thermoplastic resin filmslaminated on both sides thereof (U.S. Pat. No. 4,565,733). The thicknessof the foamed sheet is 0.3 to 2 mm, and the expansion ratio is 5 to 50times. Two uniaxially stretched films are bonded directly by heating orthrough an adhesive layer coated by hot melt coating so that respectivemolecular orientation axes cross with each other at an angle more than30 degrees. The laminated film is compressed to 40 to 85% of the sum ofrespective layers. The triple layer laminated film is excellent inimpact puncture strength and Gelbo test strength, and exhibits only aslight tendency to curl.

Since respective film layers are laminated by extrusion or usingadhesive layer in the above packaging materials, they are curled andstiffened due to the lamination. Besides, when laminated films have acoextruded T die film or inflation film, a substantial amount oftrimming loss occurs.

SUMMARY OF THE INVENTION

An object of the invention is to provide packaging materials suitablefor photosensitive materials excellent in physical strength particularlytear strength and impact puncture strength and appearance, being softand hardly curled.

Another object of the invention is to provide packaging materials ofwhich the trimming loss is low in the inflation film mold process and inthe lamination process.

Another object of the invention is to provide packaging materialswherein it is not necessary to incorporate an adhesive layer forlamination.

Another object of the invention is to provide packaging materials ofwhich the right side and the reverse side can be found readily under asafety light in a dark room where packaging is carried out.

Another object of the invention is to provide packaging materialsexcellent in the prevention of temperature elevation under sunlight.

The present invention provides packaging materials achieving suchobjects, which comprises a pair of inflation film layers disposedsymmetrically and joined through a pseudo-adhesive portion formed byblocking thereof.

The present invention also provides packaging materials which comprisesa pair of inflation film layers disposed symmetrically and joinedthrough a pseudo-adhesive portion formed by blocking thereof, and alight-reflective flexible sheet layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 7 are partially sectional views of preferred embodiments nothaving a light-reflective flexible sheet layer of the invention.

FIGS. 8 to 14 are partial sectional views of preferred embodimentshaving a light-reflective flexible sheet layer of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The layer to be blocked of the inflation film layer is preferably linearlow density polyethylene (L-LDPE) resin film layer, ethylene-acrylateester copolymer resin film layer or ethylene-vinyl acetate copolymerresin film layer.

The density of the L-LDPE resin is less than 0.925 g/cm³, preferablyless than 0.90 g/cm³. When the density is beyond 0.925 g/cm³, theadhesive strength formed by blocking is weak, even though thetemperature of molten resin is raised. Therefore, the pseudo-adhesiveportion is readily separated. The Vicat softening point of the L-LDPEresin is preferably lower than 110° C. The content of the L-LDPE resinin the film layer is preferably more than 20% by weight, furtherpreferably more than 50% by weight. The L-LDPE resin film layer maycontain other resins. Suitable other resins are EEA resin, EMA resin,LDPE resin, EAA resin, terpene resin, paraffin wax, petroleum resin,cumarone indene resin, various elastomers, etc. The L-LDPE resin filmlayer preferably contains 0.01 to 2% by weight of an antioxidant, andsuitable antioxidants are phenol antioxidants, sulfur-containingantioxidants, phosphorus-containing antioxidants and the like. Thephenol antioxidants includen-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate,2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-p-cresol (BHT),2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-thiobis(3methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol),stearyl-β-(3,5-di-4-butyl-4-hydroxyphenyl)propionate, b1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl) benzene andtetrakis methylene 3(3',5'-di-t-butyl-4'-hydroxyphenyl)propionatemethane. The sulfur-containing oxidation inhibitors includedilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate,laurylstearylthiodipropionate, distearyl-3,3'-thiodipropionate andditridecyl-3,3'-thiodipropionate. The phosphorus-containing antioxidantsinclude trinonylphenylphosphite and triphenylphosphite. Particularlyeffective antioxidants are BHT, low volatile high molecular weightphenol antioxidants ("Irganox 1010", "Irganox 1076", trade names ofCiba-Geigy A.G., "Topanol CA", trade name of I.C.I., etc.),dilaurylthiodipropionate, distearylthiodipropionate, dialkylphosphate,etc. Two or more antioxidants may be combined. An antiblocking agent isusually not added to the L-LDPE resin film layer.

The ethylene acrylate ester copolymer resin includesethylene-methylacrylate copolymer resin and ethylene-ethylacrylatecopolymer resin. The content of acrylate ester unit, such asmethylacrylate unit and ethylacrylate unit, is more than 7% by weight,preferably 7 to 30% by weight. When the content of acrylate ester unitis less than 7% by weight, it is difficult to generate blocking. It isinferior in softness, and wrinkling and furrowing are liable to occur.The physical strength is low, and the antistatic property isinsufficient. The ethylene-acrylate ester copolymer resin content of theethylene-acrylate ester copolymer resin film layer is preferably morethan 50% by weight. When the content is less than 50% by weight, thefilm layer is inferior in softness, and the adhesive strength formed byblocking is weak. Therefore, the pseudo-adhesive portion is readilyseparated. The physical strength is low, and the antistatic property isinsufficient. The ethylene-acrylate ester copolymer resin film layer maycontain other resins. Suitable other resins are L-LDPE resin, LDPEresin, EAA resin, terpene resin, paraffin wax, cumarone indene resin,various elastomers, etc. The ethylene-acrylate ester copolymer resinfilm layer preferably contains 0.01 to 2% by weight of an antioxidant,and the antioxidant may be selected from described previously. When thecontent is less than 0.01% by weight, oxidation inhibition isinsufficient. The generation of the lumps of antioxidant increases dueto the oxidation of resin, and the lumps cause pressure marks on thephotographic photosensitive materials packaged therein. While, when thecontent is beyond 2% by weight, the antioxidant adversely affects thephotographic photosensitive materials utilizing an oxidation-reductionreaction. The antioxidant gradually bleeds out. An antiblocking agent isusually not added to the ethylene-acrylate ester copolymer resin filmlayer.

The vinyl acetate unit content of the ethylene-vinyl acetate copolymerresin is more than 5% by weight, preferably 5 to 35% by weight. When thecontent is less than 5% by weight, it is difficult to generate blocking.The adhesive strength formed by blocking is weak, and thepseudo-adhesive portion is readily separated during bag-making, etc. Theethylene-vinyl acetate copolymer resin content of the film layer ispreferably more than 50% by weight. When the content is less than 50% byweight, the film layer is inferior in softness, and the adhesivestrength formed by blocking is weak. Therefore, the pseudo-adhesiveportion is readily separated. The ethylene-vinyl acetate copolymer resinfilm layer may contain other resins. Suitable other resins are L-LDPEresin, LDPE resin, EMA resin, EEA resin, EAA resin, terpene resin,paraffin wax, petroleum resin, cumarone indene resin, variouselastomers, etc. An antiblocking agent is usually not added to theethylene-vinyl acetate copolymer resin film layer.

The thickness of the inflation film layer is usually 15 to 200 μm,particularly 20 to 100 μm, in the case of a coextruded multilayer filmlayer.

The inflation film layers are molded by the inflation process, and theinside of the molded tubular film is joined through a pseudo-adhesiveportion formed by blocking. That is, the inflation film layers aresymmetrically joined without using an adhesive. In the packagingmaterial of the invention, it is sufficient that the inner layers of theinflation film layers are joined by the pseudo-adhesion formed byblocking, and the blocking area is preferably more than 50%, furtherpreferably more than 95%, in view of the prevention of wrinkling,thickening, laminating ability, lay-making ability and the like. Theyare joined in a flexible state, and the adhesive strength may be in therange from the lightly joined state to the maximum heat strength in thecase that the inflation films are joined by heat seal at a suitabletemperature. Preferable adhesive strength is 0.01 to 1000 g/15 mm width,and particularly preferable adhesive strength is 0.1 to 300 g/15 mmwidth, when it is measured according to the testing method ofdelamination resistance described in U.S. Pat. No. 4,708,896. When theblocking is too weak, the inflation films separate during variousprocesses, and wrinkling, thickening, slippage or the lie occurs. While,the blocking strength is too great, the laminated film formed byblocking becomes like a single layer film, physical strength is lowered.The laminated film becomes stiff, and bursting strength decreases.Therefore, the resin composition of the inner layer may be sufficient tosatisfy the above characteristics. Preferably the resin compositioncontains one or more resins selected from low density polyethylene resinincluding L-LDPE resin and LDPE resin having a density of less than0.925 g/cm³ and a Vicat softening point of lower than 110° C.,ethylene-acrylate ester copolymer resin having a comonomer content ofmore than 7% by weight, ethylene-vinyl acetate copolymer resin having acomonomer content of 5% by weight, EEA resin, terpene resin, paraffinwax, petroleum resin, cumarone indene resin and various elastomers. Inthe case of the above resin, composition, an antiblocking agent may beincorporated. However, in order to make the blocking completely, theantiblocking agent is preferably not incorporated. The pseudo-adhesiveportion may contain space, and in this case, buffer action can beobtained by the space.

The blocking is made to occur by passing the take-up nip roll or apressure roll newly incorporated before and/or after the nip roll or thelike. The occurrence and adjustment of the strength of pseudo-adhesionis made by selecting the kind of resin, the density, the Vicat softeningpoint and other properties, particularly the density, of the resin,additives, particularly a decrease in or absence of antiblocking agent,temperature relations, such as molten resin temperature, the temperatureof cooling medium such as blown air or water, and room temperature, thelength between the round die and the blocking part, nipping pressure,heating roll pressure, and the like.

The inflation film layer is, in general, a coextruded multilayer filmlayer in order to prevent the blocking on the outside of the inflationfilm layer. A preferable outer layer is the heat-sealable thermoplasticresin film layer containing more than 10% by weight of an ethylenecopolymer resin, a light-shielding material and a lubricant. Moreover,it is preferable to incorporate more than 0.5% by weight of polyethyleneresin having a density of 0.940 g/cm³ in the resin composition of theouter layer because blocking can be prevented without antiblockingagent. The softening point, Young's modulus, wear resistance, etc. canalso be improved. The Vicat softening point of the outer layer is higherthan the inner layer to be blocked by 5° C. or more, and the slip angleof the outer layer is preferably 6 to 60 degrees.

The ethylene copolymer resin includes ethylene propylene copolymerresin, L-LDPE resin, ethylene-ethylacrylate copolymer resin,ethylene-methylacrylate copolymer resin, ethylene-vinyl acetatecopolymer resin, ethylene acrylic acid copolymer resin, and the like.The ethylene copolymer resin content of the thermoplastic resin filmlayer is more than 10% by weight, preferably 10 to 99% by weight. In thecase of less than 10% by weight, when the content of a light-shieldingmaterial and a lubricant is high, delamination resistance is small, andphysical strength remarkably decreases. The thermoplastic resin filmlayer may contain other resins. Suitable other resins are variouspolyethylene resins, various polypropylene resins, polyvinyl chlorideresin, polyvinylidene chloride resin, various polyamide resins,polycarbonate resin, various polyester resins, modified polyolefinresins and blended resins thereof.

The light-shielding material includes every material capable ofshielding visible, infrared and ultraviolet light. Examples of thelight-shielding material are various carbon black, graphite, iron oxide,zinc white, titanium oxide, clay, aluminum powder, aluminum paste,calcium carbonate, mica, barium sulfate, talc, cadmium pigments, rediron oxide, cobalt blue, copper-phthalocyanine pigments, monoazo andpolyazo pigments and aniline black. Various carbon black, aluminumpowder and aluminum paste from which volatile components are removed arepreferred in view of light-shielding ability, quality, cost and thelike. Among these, oil furnace carbon black having a mean particle sizeof smaller than 200 mμ is preferred in terms of light-shielding ability,cost and improvement of physical strength. On the other hand, sinceacetylene carbon black, Ketschen carbon black and graphite haveantistatic character, they are also preferred, though they areexpensive. They may be blended with the oil furnace carbon black inorder to improve its character. Suitable pH of carbon black is at 5 to9, and suitable mean particle size is 10 to 120 mμ, particularly 10 to50 mμ. The oil furnace carbon black having pH 6 to 9 and mean particlesize of smaller than 50 mμ is preferred. By using the carbon black ofsuch pH and particle size, a packaging material having the followingmerits is obtained. That is, the occurrence of fogging is rare, increaseor decrease of photosensitivity scarcely happens, light shieldingability is great, the lumps of carbon black and pinholes such as fisheyes hardly occur, and physical strength and heat sealing properties areimproved. As the preferable light-shielding material, metal powder is insecond place. Metal powder is a light-reflective light-shieldingmaterial. It imparts silver appearance being preferable, and it isexcellent in moistureproofness, light-shielding, antistatic property,thermal shielding in the sunlight and gas barrier. As the metal powder,aluminum powder and its paste are preferable. The paste of aluminumpowder is produced by adding mineral spirits and a small amount of ahigher fatty acid such as stearic acid or oleic acid or a derivativethereof to form paste at the production of aluminum powder according toa known method such as using a ball mill, a stamp mill or an atomizer. Apolyolefin thermoplastic resin, such as various polypropylene resins,various polyethylene resins, ethylene-vinyl acetate copolymer (EVA)resin, ethylene-ethyl acrylate copolymer (EEA) resin andethylene-acrylic acid copolymer (EAA) resin, or another thermoplasticresin is kneaded together with this aluminum paste under heating, andvolatile components mainly mineral spirits are removed by heating and/ora vacuum pump. This product is used as aluminum paste compound resin oraluminum paste masterbatch resin. The aluminum powder includesmicroflakes produced from aluminum foil which is crushed by a ball millor a stamp mill, in addition to usual aluminum powder manufactured byatomization, dropping on a rotary disc or evaporation from meltedaluminum. Since aluminum powder is unstable, it is stabilized by a knowntreatment, such as coating with a higher fatty acid, a derivativethereof or the like. The content of the light-shielding material is 0.5to 50 g/m². The form of the light-shielding material prior to blendingmay be powder, paste, liquid, dye color granule, masterbatch pellets,etc. As the method of blending the light-shielding material, there arethe masterbatch method, dye color granule method, the compound coloringmethod and the like. The light-shielding material may be added to otherlayers including the foregoing inner layer.

The lubricant is added in order to improve film moldability, slippingcharacter, processibility, and the like. The lubricant may be selectedfrom fatty acid amide lubricants such as oleic acid amide lubricants,erucic acid amide lubricants, stearic acid amide lubricants and bisfatty acid amide lubricants, silicone lubricants, alkylamine lubricants,fatty acid metallic salts, waxes, paraffins, fatty alcohols, glycerides,fatty acid lower alcohol esters, α-olefin-maleic acid copolymers, andthe like.

Examples of commercial lubricants suitable for the present inventioninclude:

Oleic acid amide lubricants; "ARMOSLIP-CP" (Lion akzo Co., Ltd.),"NEWTRON" and "NEWTRON E-18" (Nippon Fine Chemical Co., Ltd.), "AMIDE-0"(Nitto Kagaku K.K.), "DIAMID 0-200" and "DIAMID G-200" (Nippon KaseiChemical Co., Ltd.), "ALFLOW E-10" (Nippon Oil and Fats Co., Ltd.), etc.

Erucic acid amide lubricants; "ALFLOW P-10" (Nippon Oil and Fats Co.,Ltd.), "NEWTRON S" (Nippon Fine Chemical Co., Ltd.), etc.

Stearic acid amide lubricants; "ALFLOW S-10" (Nippon Oil and Fats Co.,Ltd.), "NEWTRON 2" (Nippon Fine Chemical Co., Ltd.), "DIAMID 200"(Nippon Kasei Chemical Co., Ltd.), etc.

Bis fatty acid amide lubricants; "BISAMIDE" (Nitto Kagaku K.K.), "DIAMID200 BIS" (Nippon Kasei Chemical Co., Ltd.), "ARMOWAX-EBS" (Lion AkzoCo., Ltd.), etc.

Silicone lubricants; Dimethylpolysiloxanes, etc. (Sinetsu Chemical Co.,Ltd., Toray Silicone Co., Ltd.), etc.

Alkylamine lubricants; "ELECTROSTRIPPER TS-2" (Kao Corp.) etc.

Preferable lubricants include the fatty acid amide lubricants having anumber of carbon atoms of 8 to 50, preferably 15 to 35. Two or morelubricants may be combined. When the packaging material is used forphotographic photosensitive materials, a suitable content of thelubricant is 0.01 to 1% by weight. The lubricant may be added to variouslayers.

The Vicat softening point (Testing method for Vicat softeningtemperature of thermoplastics ASTM D-1525) of the thermoplastic resinfilm layer is preferably higher than the inner layer to be blocked by 5°C. or more. By the difference of the softening points, the inner layersjoined by pseudo-adhesion can sufficiently be melted at the heat sealportion, all layers are thus joined completely. The difference is alsopreferably in view of the occurrence of blocking.

The slip angle of the thermoplastic resin film layer is preferably 6 to60 degrees in order to improve slipperiness and to prevent wrinklingduring forming the inflation film, laminating to other film layers,bag-making, packaging and the like. The measuring procedure of the slipangle is described later. When the slip angle is less than 6 degrees,weaving occurs at the winding of the laminated film. Moreover, thelaminated film cannot be stacked. While, when the slip angle is beyond60 degrees, wrinkling or furrowing occurs during forming the inflationfilm. Various troubles happen during packaging process and otherprocesses.

A substance having antiblocking activity (antiblocking substance) ispreferably incorporated into the thermoplastic resin film layer. Such anantiblocking substance includes antiblocking agents, such as silica,diatomaceous earth, talc, calcium silicate, aluminum silicate, magnesiumsilicate, calcium carbonate, polyvinyl esters of higher fatty acid,n-octadecylurea, dicarboxylic acid ester amides andN,N'-dioleylhydroxyamido, and various lubricants and light-shieldingmaterials having antiblocking activity. Preferable antiblockingsubstances are carbon black, fatty acid amides, silica, talc, calciumcarbonate, metal powder, titanium dioxide and the like. When theantiblocking substance and the polyethylene resin having a density ofmore than 0.925 g/cm³ is absent in the outer layer, blocking is liableto occur between the outer layers all over the roll of the inflationfilm of the invention during winding and temporary stock.

When the outer layer contains the antiblocking substance, the outerlayer may be another thermoplastic resin film layer not containingethylene copolymer resin, such as various polyethylene resin filmlayers, various polypropylene resin film layers, polyvinyl chlorideresin film layer, polyvinylidene chloride resin film layer, variouspolyamide resin film layers, polycarbonate resin film layer, variouspolyester resin film layers, various their modified resin film layers orvarious their blended resin film layers.

The thickness of the thermoplastic resin film layer is usually 10 to 190μm, particularly 20 to 100 μm. In the case of the laminated film formedby blocking, the thickness doubles.

The coextruded multilayer film layer may contain one or moreintermediate layers. In the packaging material of the invention, sincethe outer layer is disposed on both sides, the inner layer andintermediate layers may contain harmful materials for the product to bepackaged.

When a multilayer film is coextruded by a round die inflation moldingmachine, the laminating methods are divided broadly into three types,i.e. laminating in die type, laminating out of die type and laminar flowsupply type. The laminating in die type is preferable because of strongdelamination resistance.

Various flexible sheet layers may be laminated to the paired inflationfilm layers joined by the pseudo-adhesion. Such a flexible sheetincludes uniaxially or biaxially molecularly oriented (includingstretched) or unstretched various thermoplastic resin films such asvarious polyethylene resin films, various ethylene copolymer resinfilms, various polypropylene resin film, polyvinyl chloride resin film,polyvinylidene chloride resin film, various polyamide resin films,polycarbonate resin film, various polyester resin films, various theirmodified resin films and various their blended resin films, metallizedfilms represented by aluminum vacuum-metallized film, cellulose acetatefilm, cellophane, polyvinyl alcohol film, various papers, various metalfoils represented by aluminum foil, nonwoven fabric, and the like.

A particularly preferable flexible sheet layer to be laminated is alight-reflective flexible sheet layer disposed as the outer layer or atthe position capable of looking from the outside. The light-reflectiveflexible sheet layer is composed of a metal foil layer, a metallizedflexible sheet layer, a light-reflective light shielding thermoplasticresin film layer containing a light-reflective light-shielding materialor a combination thereof. The metal foil is aluminum foil, tin foil,iron foil or the like, and the metallized flexible sheet is aluminumvacuum-metallized film, aluminum vacuum metallized paper, sputteringfilm or the like.

The thermoplastic resin of the light-reflective light-shieldingthermoplastic resin film layer may be a polyolefin resin, a polyesterresin, a polyamide resin or the like, and polyolefin resins arepreferable. Particularly preferable resins are high density polyethylene(HDPE) resin, polypropylene resin, L-LDPE resin and blended resinscontaining one or more of these resins, being excellent inmoistureproofness. The light-reflective light-shielding material ismetal powder, white or light yellow pigment, or the like. The metalpowder is aluminum powder, aluminum paste, tin powder, nickel powder,zinc powder, the powder of the alloy or compound thereof. The aluminumpowder and aluminum paste may be the same as explained previously. Aparticularly preferable light-reflective light-shielding material is thealuminum powder completely coated with a higher fatty acid, a higherfatty acid derivative or a mixture thereof, which is prepared byblending 90 to 99.9% by weight of aluminum powder with 0.1 to 10% byweight of a higher fatty acid, a higher fatty acid derivative or amixture thereof without using a solvent such as mineral spirit. Thecontent of metal powder is usually 0.1 to 20% by weight, and 1 to 6% byweight is preferable.

The thickness of the light-reflective flexible sheet layer is more than5 μm, preferably 8 to 80 μm, more preferably 10 to 50 μm in view oflaminating ability.

The flexible sheet layer including the light-reflective flexible sheetlayer may be laminated according to a known method such as a heatsealing (hot bar sealing, Verneuil's method, impulse heat sealing,supersonic heat sealing, etc.) or the method using an adhesive (wetlaminating, dry laminating, hot melt laminating, extrusion laminating,etc.).

The adhesive is selected by considering both layers to be joined, andincludes thermoplastic resin melting adhesives including a polyolefinadhesive, hot melt type gum adhesives and solution type adhesives. Thepolyolefin adhesives include a homopolymer and a copolymer of an olefinsuch as various polyethylenes, polypropylenes, polybutenes andethylene-propylene copolymers and L-LDPE, a copolymer of an olefin andanother monomer such as ethylene-vinyl acetate copolymer,ethylene-acrylate ester copolymer, various ionomers ("SURLYN" Dupont,"HIMIRAN" Mitsui Polychemicals Co., Ltd., etc.) and a graft copolymer.The solution type adhesives are divided into adhesives for wetlamination and adhesives for dry lamination™The adhesives for wetlamination are emulsion or latex. Examples of the emulsion-typeadhesives are polyvinyl acetate emulsion, the emulsion of vinylacetate-ethylene copolymer, the emulsion of vinyl acetate-acrylate estercopolymer, the emulsion of vinyl acetate-maleate ester copolymer, theemulsion of acrylic copolymer and the emulsion of ethylene-acrylic acidcopolymer. Examples of the latex-type adhesives are natural rubberlatex, styrene-butadiene rubber latex, acrylonitrile-butadiene rubberlatex and chloroprene rubber latex. An example of the adhesives for drylamination is polyurethane adhesive. Adhesives for hot melt laminationcontaining paraffin wax, microcrystalline wax, ethylene-vinyl acetatecopolymer and ethylene-ethylacrylate copolymer, pressure-sensitiveadhesives, temperature-sensitive adhesives and ultraviolet curing typeadhesives may also be employed. Particularly preferable extrusionlaminating adhesives are LDPE resin and L-LDPE resin due to theirexcellent laminating ability and inexpensiveness. Besides, a blend ofresins of the foregoing resins for adhesive so as to compensate thedefect of each resin is also particularly preferable.

The thickness of the adhesive layer formed by extrusion laminating usinga thermoplastic resin is usually 6 to 50 μm, preferably 10 to 20 μm.However, the thickness is determined based upon cost, rate ofapplication, thickness of the whole layers, and etc., and accordingly,the thickness is not limited to the above range.

The packaging material of the invention may be used for packagingphotosensitive materials such as photographic photosensitive materials,foods, medicines or chemical substances, and it is particularly suitablefor packaging silver halide photographic photosensitive materials, diazophotographic photosensitive materials, photosensitive resins,self-developing type photographic photosensitive materials and otherphotographic materials which are degraded by small amounts of moistureor gas.

The package form my be conventional and includes a single-sheet flatbag, a double-sheet flat bag, a self-standing bag, a single-sheet gussetbag, a double-sheet gusset bag, inner lining for a moisture proof box,inner lining for a light room-loading light-shielding box and a leaderpaper. The sealing form may also be conventional, and includes heatsealing, heat cut sealing, impulse heat sealing, supersonic sealing andhigh frequency sealing. The methods of using an adhesive may also beutilized.

In the packaging materials of the invention, a pair of inflation filmlayers is joined to each other by blocking in a flexible state to somedegree without using adhesive. Therefore, they are not always joinedcompletely integrally, and a little space remains between the inflationfilm layers. The space can be increased by controlling the properties ofthe inflation film layers, blocking conditions and the like. By thispseudo-adhesion, physical strength such as tear strength is improved,buffer action is imparted, and curling is prevented. The thermoplasticresin film layer improves film moldability and shields the order of theinner layer such as ethylene-acrylate ester resin film layer orethylene-vinyl acetate resin film layer. The light-reflective flexiblesheet layer improves printability, right-reverse judgement under safetylight, and the prevention of high internal temperatures under sunlight.

The packaging materials of the invention are flexible and excellent inphysical strength such as tear strength, Gelbo test strength, burstingstrength and impact puncture strength. Curling does not occurs, and inthe case of the pseudo-adhesion alone, the equipment for the adhesionusing an adhesive is not necessary. Moreover, in the case of using theethylene-acrylate ester copolymer resin film layers for thepseudo-adhesion, antistatic property is also improved, and undesirableorder of the ethylene-acrylate ester copolymer resin can be shielded bythe thermoplastic resin film layer. In the case of using theethylene-vinylacetate copolymer resin film layers for thepseudo-adhesion, the problems of the EVA resin such as inferiormoldability, the blocking in the case of winding the film, andundesirable order are also improved. By incorporating thelight-reflective flexible sheet layer, antistatic property is alsoimproved. Since the packaging materials of the invention are produced byjoining the insides of inflation film, the edge trimming loss in thecase of a conventional inflation film mold process and laminated filmsdoes not occur. Since the laminated film of the invention is produced byan inflation molding process, it can be efficiently utilized. Wrinklingand melt fracture hardly occur, and film moldability is good.

The packaging materials of the invention are characterized by thecoextruded multilayer inflation film having a particular layercombination and an antiblocking substance incorporated into the outerlayers, while antiblocking agent is excluded from the inner layers.Preferable embodiments of the packaging material of the inventioninclude:

(1) A packaging material which comprises a pair of coextruded multilayerinflation film layers disposed, symmetrically each comprising a linearlow density polyethylene resin film layer containing more than 50% byweight of linear low density polyethylene resin having a density of lessthan 0.925 g/cm³ and 0.01 to 2% by weight of an antioxidant disposed onthe inside joined through a pseudo-adhesive portion formed by blockingand a thermoplastic resin film layer containing a substance havingantiblocking activity disposed on the outside.

(2) A packaging material which comprises the laminated film of the aboveembodiment (1) and a light-reflective flexible sheet layer.

(3) A packaging material which comprises a pair of coextruded multilayerinflation film layers disposed symmetrically each comprising anethylene-acrylate ester copolymer resin film layer containing preferablymore than 50% by weight of an ethylene-acrylate ester copolymer resinfilm layer. An ethylene-acrylate ester copolymer resin of which thecontent of methylacrylate unit, ethylacrylate unit or a mixture thereofis more than 7% by weight and 0.01 to 2% by weight of an antioxidantdisposed on the inside joined through a pseudo-adhesive portion formedby blocking and a thermoplastic resin film layer containing a substancehaving antiblocking activity disposed on the outside.

(4) A packaging material of which comprises the laminated film of theabove embodiment (3) and a light-reflective flexible sheet layer.

(5) A packaging material which comprises a pair of coextruded multilayerinflation film layers disposed symmetrically each comprising anethylene-vinyl acetate copolymer resin film layer containing more than35% by weight of ethylene-vinyl acetate copolymer resin of which thecontent of vinyl acetate unit is more than 5% by weight disposed on theinside joined through a pseudo-adhesive portion formed by blocking and athermoplastic resin film layer containing a substance havingantiblocking activity disposed on the outside.

(6) A packaging material which comprises the laminated film of the aboveembodiment (5) and a light-reflective flexible sheet layer.

Representative embodiments of the packaging materials of the inventionare illustrated in FIGS. 1 to 14.

The packaging material of FIG. 1 is composed of a pair of coextrudedmultilayer inflation films 3,3 consisting of an inner layer 1 which isa-L LDPE resin film layer, an ethylene-acrylate ester copolymer resinfilm layer or an ethylene-vinyl acetate copolymer resin film layer andan outer layer 2 which is a thermoplastic resin film layer 2. Thecoextruded multilayer inflation film is molded by a double layercoextrusion inflation film molding machine using a round die. The innerlayers 1,1 are joined to each other through the pseudo-adhesion portion5 formed by blocking.

The packaging material of FIG. 2 is the same as the packaging materialof FIG. 1, except that the thermoplastic resin film layer 2a haslight-shielding ability.

The packaging material of FIG. 3 is the same as the packaging materialof FIG. 1, except that both of the inner layer 1a and the thermoplasticresin film layer 2a have light-shielding ability.

The packaging material of FIG. 4 is the same as the packaging materialof FIG. 1, except that the inner layer 1a has light-shielding ability.

The packaging material of FIG. 5 is the same as the packaging materialof FIG. 1, except that the coextruded multilayer inflation film 3 is atriple layer film where an intermediate layer 4 is incorporated.

The packaging material of FIG. 6 is the same as the packaging materialof FIG. 3, except that the coextruded multilayer inflation film 3a is atriple layer film where a light-shielding intermediate layer 4a isincorporated.

The packaging material of FIG. 7 is the same as the packaging materialof FIG. 2, except that the coextruded multilayer inflation film 3a is aquadruple layer film with intermediate layer 41 located on the insideand on other intermediate layer 42a having light-shielding abilitylocated on the outside.

The packaging materials of FIGS. 8 to 14 are formed by laminating thelight-reflective flexible sheet layer 6 to the packaging material ofFIGS. 1 to 7 through an adhesive layer 7, respectively.

EXAMPLES EXAMPLES IN THE CASE OF L-LDPE RESIN FILM LAYER Example I

The packaging material of Example I corresponds to the embodiment ofFIG. 2.

The inner layer 1 is the L-LDPE resin film layer composed of 20% byweight of L-LDPE resin of which α-olefin is butene-1 having a density of0.890 g/cm³, a MI of 1.0 g/10 minutes and a Vicat softening point of 75C, 79.7% by weight of L-LDPE resin of which α-olefin is4-methylpentene-1 having a density of 0.920 g/cm³, a MI of 2.1 g/10minutes and a Vicat softening point of 100° C. and 0.3% by weight ofantioxidant. The thickness of the inner layer 1 is 25 μm.

The thermoplastic resin film layer 2a is composed of 20% by weight ofHDPE resin having a density of 0.954 g/cm³, a MI of 1.1 g/10 minutes anda Vicat softening point of 126° C., 76.75% by weight of L-LDPE resin ofwhich α-olefin is 4-methylpentene-1 having a density of 0.920 g/cm³, aMI of 2.1 g/10 minutes and a Vicat softening point of 100° C., 3% byweight of carbon black and 0.05% by weight of oleic acid amide and 0.25%by weight of antioxidant. The thickness of the thermoplastic resin filmlayer 2a is 25 μm.

Example II

The packaging material of Example II corresponds to the embodiment ofFIG. 3.

The inner layer 1 is the L LDPE resin film layer composed of 96.7% byweight of L-LDPE resin of which α-olefin is 4-methylpentene-1 having adensity of 0.9111 g/cm³, a MI of 2.0 g/10 minutes and a Vicat softeningpoint of 88° C., 3% by weight of carbon black and 0.3% by weight ofantioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example I.

Example III

The packaging material of Example III corresponds to the embodiment ofFIG. 3.

The inner layer 1 is the L LDPE resin film layer composed of 96.7% byweight of L-LDPE resin of which α-olefin is 4-methylpentene-1 having adensity of 0.910 g/cm³, a MI of 3.5 g/10 minutes and a Vicat softeningpoint of 86° C., 3% by weight of carbon black and 0.3% by weight ofantioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example I.

Example IV

The packaging material of Example IV corresponds to the embodiment ofFIG. 3.

The inner layer 1 is the L-LDPE resin film layer composed of 96.7% byweight of L-LDPE resin of which α-olefin is 4-methylpentene-1 having adensity of 0.911 g/cm³, a MI of 1.95 g/10 minutes and a Vicat softeningpoint of 88° C. and 3% by weight of carbon black and 0.3% by weight ofantioxidant, and its thickness is 30 μm.

The thermoplastic resin film layer 2a is composed of 5% by weight ofLDPE resin having a density of 0.923 g/cm³, a MI of 2.4 g/10 minutes anda Vicat softening point of 92° C., 91.75% by weight of HDPE resin havinga density of 0.964 g/cm³, a MI of 0.4 g/10 minutes and a Vicat softeningpoint of 128° C. and 3% by weight of carbon black and 0.25% by weight ofantioxidant, and its thickness is 20 μm.

Example V

The packaging material of Example V corresponds to the embodiment ofFIG. 3.

The inner layer 1 is the L-LDPE resin film layer composed of 20% byweight of L-LDPE resin of which α-olefin is 4-methylpentene-1 having adensity of 0.935 g/cm³, a MI of 2.1 g/10 minutes and a Vicat softeningpoint of 113° C., 76.65% by weight of L LDPE resin of which α-olefin is4-methylpentene-1 having a density of 0.911 g/cm³, a MI of 1.95 g/10minutes and a Vicat softening point of 88° C., 3% by weight of carbonblack and 0.05% by weight of oleic acid amide and 0.3% by weight ofantioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example III.

COMPARATIVE EXAMPLE I

The packaging material of comparative Example I is a coextruded doublelayer film composed of the layer having the same resin composition asthe L-LDPE resin film layer of Example IV and a thickness of 50 μm andthe layer having the same resin composition as the thermoplastic resinfilm layer of Example IV and a thickness of 50 μm.

In this specification, MI, density and Vicat softening point weremeasured according to the following method, unless specificallymentioned.

MI (g/10 minutes); ASTM D-1238 (at 190° C.).

Density (g/cm³); ASTM D-1505.

Vicat Softening Point (°C.); ASTM D-1525.

Various properties of the above packaging materials were measured, andthe results are summarized in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                     Invention           Comparative                                               I   II  III IV  V   I                                        __________________________________________________________________________    Layer Composition                                                                              FIG. 2                                                                            FIG. 3                                                                            FIG. 3                                                                            FIG. 3                                                                            FIG. 3                                                                            --                                       Inner Layer Thickness (μm)                                                                  25 × 2                                                                      25 × 2                                                                      25 × 2                                                                      30 × 2                                                                      25 × 2                                                                      50                                       Outer Layer Thickness (μm)                                                                  25 × 2                                                                      25 × 2                                                                      25 × 2                                                                      20 × 2                                                                      25 × 2                                                                      50                                       Smoothness       B   B   B   B   B   D-E                                      Curling          0 (A)                                                                             0 (A)                                                                             0 (A)                                                                             0 (A)                                                                             0 (A)                                                                             1.1 (C)                                  Film Moldability B-C B   B   B   B   D-E                                      Tear Strength MD (g)                                                                           >1600                                                                             >1600                                                                             >1600                                                                             847 >1600                                                                             236                                      Tear Strength CD (g)                                                                           >1600                                                                             >1600                                                                             >1600                                                                             >1600                                                                             >1600                                                                             >1600                                    Gelbo Test Strength (Times)                                                                     >300                                                                              >300                                                                              >300                                                                              >300                                                                              >300                                                                              >300                                    Bursting Strength (kg/cm.sup.2)                                                                2.28                                                                              2.60                                                                              2.32                                                                              2.57                                                                              2.78                                                                              2.62                                     Static Friction Right (tan θ)                                                            0.133                                                                             0.133                                                                             0.133                                                                             0.117                                                                             0.128                                                                             0.117                                    Coefficient                                                                   Static Friction Reverse (tan θ)                                                          "   "   "   "   "   1.600                                    Coefficient                                                                   Impact Puncture Strength (kg · cm)                                                    >30 >30 >30 >30 >30 23                                       __________________________________________________________________________

Evaluations in Table 1 were carried out as follows:

    ______________________________________                                        A      very excellent  B     excellent                                        C      practical       D     having a problem                                 E      impractical                                                            ______________________________________                                    

Testing methods were as follows:

Thickness; JIS P-8118.

Smoothness:

Each sample was molded using a simultaneously coextruding double layerinflation molding machine, and the smoothness was judge by the degreemelt fracture generation.

Curling:

Each test piece having a width of 80 cm and a length of 1 m was hungperpendicularly, and the curling was judge by the curling state of eachtest piece (Judged by the processibility for a processing machine).

Film Moldability:

Each sample was molded using a simultaneously coextruding double layerinflation molding machine, and the film moldability was judged bycurrent load, bubble stability, wrinkling and the like.

Tear strength; JIS P-8116.

Gelbo Test Strength; U.S. Military Standard MIL 131.

Bursting Strength; JIS P-8112.

Static Friction coefficient (Slip Angle):

A part of each exemplified film was cut off, and stuck on the undersideof 75 mm length×35 mm width of a stainless steal block weighing 200 g byusing a double face adhesive tape. Another part of the sample was stuckon an inclined face, and the above block was placed on the face. Theinclined angle was increased, and the angle (θ) where the block began toslip was read. The coefficient is represented by the tangent.

Impact Puncture Strength; JIS P-8134.

Examples In The Case Of Ethylene-Acrylate Ester Copolymer Resin FilmLayer Example VI

The packaging material of Example VI corresponds to the embodiment ofFIG. 2.

The inner layer 1 is the ethylene-acrylate ester copolymer resin filmlayer composed of 69.7% by weight of EEA resin of which the comonomerunit content is 18% by weight having a density of 0.93 g/cm³, a MI of 6g/10 minutes and a Vicat softening point of 56° C., 30% by weight ofL-LDPE resin of which α-olefin is octene-1 having a density of 0.920g/cm³, a MI of 2 g/10 minutes and a Vicat softening point of 96° C. and0.3% by weight of antioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is composed of 20% by weight ofHDPE resin having a density of 0.954 g/cm³, a MI of 1.1 g/10 minutes anda Vicat softening point of 126° C., 76.75% by weight of L LDPE resin ofwhich α-olefin is 4-methylpentene-1 having a density of 0.920 g/cm³, aMI of 2.1 g/10 minutes and a Vicat softening point of 100° C., 3% byweight of carbon black and 0.05% by weight of oleic acid amide and 0.25%by weight of antioxidant, and its thickness is 25 μm.

Example VII

The packaging material of Example VII corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene acrylate ester copolymer resin filmlayer composed of 59.7% by weight of EEA resin of which the comonomerunit content is 10% by weight having a density of 0.93 g/cm³, a MI of1.5 g/10 minutes and a Vicat softening point of 61° C., 38% by weight ofL-LDPE resin of which α-olefin is butene-1 having a density of 0.890g/cm³, a MI of 1 g/10 minutes and a Vicat softening point of 58° C. and2% by weight of carbon black and 0.3% by weight of antioxidant, and itsthickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example VI.

Example VIII

The packaging material of Example VIII corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene-acrylate ester copolymer resin filmlayer composed of 59.7% by weight of EEA resin of which the comonomerunit content is 20% by weight having a density of 0.93 g/cm³, a MI of 20g/10 minutes and a Vicat softening point of 50° C., 37% by weight ofL-LDPE resin and 3% by weight of carbon black and 0.3% by weight ofantioxidant and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example VI.

Example IX

The packaging material of Example IX corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene-acrylate ester copolymer resin filmlayer of which the resin composition is the same as the packagingmaterial of Example VII, and its thickness is 30 μm.

The thermoplastic resin film layer 2a is composed of 5% by weight ofLDPE resin having a density of 0.923 g/cm³, a MI of 2.4 g/10 minutes anda Vicat softening point of 92° C., 91.75% by weight of HDPE resin havinga density of 0.964 g/cm³, a MI of 0.4 g/10 minutes and a Vicat softeningpoint of 128° C. and 3% by weight of carbon black 0.25% by weight ofantioxidant, and its thickness is 20 μm.

Example X

The packaging material of Example X corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene acrylate ester copolymer resin filmlayer composed of 59.7 % by weight of EEA resin of which the comonomerunit content is 20% by weight having a density of 0.93 g/cm³, a MI of 20g/10 minutes and a Vicat softening point of 50° C., 38% by weight ofL-LDPE resin of which α-olefin is 4-methylpentene-1 having a density of0.920 g/cm³, a MI of 2.1 g/10 minutes and a Vicat softening point of100° C. and 2% by weight of carbon black and 0.3% by weight ofantioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example VIII.

Comparative Example II

The packaging material of Comparative Example II is a coextruded doublelayer film composed of the layer having the same resin composition asthe ethylene-acrylate ester copolymer resin film layer of Example IX anda thickness of 50 μm and the layer having the same resin composition asthe thermoplastic resin film layer of Example IX and a thickness of 50μm.

Various properties of the above packaging materials were measured, andthe results are summarized in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                     Invention               Comparative                                           VI    VII VIII                                                                              IX    X   II                                   __________________________________________________________________________    Layer Composition                                                                              FIG. 2                                                                              FIG. 3                                                                            FIG. 3                                                                            FIG. 3                                                                              FIG. 3                                                                            --                                   Inner Layer Thickness (μm)                                                                  25 × 2                                                                        25 × 2                                                                      25 × 2                                                                      30 × 2                                                                        25 × 2                                                                      50                                   Outer Layer Thickness (μm)                                                                  25 × 2                                                                        25 × 2                                                                      25 × 2                                                                      20 × 2                                                                        25 × 2                                                                      50                                   Smoothness       B     B   B   B     B   C-D                                  Curling          O (A) O (A)                                                                             O (A)                                                                             O (A) O (A)                                                                             2.5 (D)                              Film Moldability B     B   B   B     B   C-D                                  Tear Strength MD (g)                                                                           1385  >1600                                                                             >1600                                                                             603   >1600                                                                             187                                  Tear Strength CD (g)                                                                           >1600 >1600                                                                             >1600                                                                             >1600 >1600                                                                             >1600                                Gelbo Test Strength (Times)                                                                    >300  >300                                                                               >300                                                                             >300  >300                                     Slip Angle Reverse (degrees)                                                                   11      11                                                                                11                                                                               9      10                                                                               9                                   Slip Angle Right (degrees)                                                                     11      11                                                                                11                                                                               9      10                                                                              58                                   Impact Puncture Strength (kg · cm)                                                    28    >30 >30  25   >30 19                                   __________________________________________________________________________

In Table 2, the evaluations and the testing methods are the same asthose in Table 1. The slip angle was measured in the same manner as thestatic friction coefficient, and the angle (θ) where the block began toslip is written in Table 2 as the slip angle.

Examples In The Case Of Ethylene-Vinyl Acetate Copolymer Resin FilmLayer Example XI

The packaging material of Example XI corresponds to the embodiment ofFIG. 2.

The inner layer 1 is the ethylene-vinyl acetate copolymer resin filmlayer composed of 69.7% by weight of EVA resin of which vinyl acetateunit content is 14% by weight (saponification method) having a MFR of3.5 g/10 minutes, a density of 0.93 g/cm³ and a Vicat softening point of68° C. and 30% by weight of L LDPE resin of which α-olefin is octene-1having a density of 0.920 g/cm³, a MI of 2 g/10 minutes and a Vicatsoftening point of 96° C. and 0.3% by weight of antioxidant, and itsthickness is 25 μm.

The thermoplastic resin film layer 2a is composed of 20% by weight ofHDPE resin having a density of 0.954 g/cm³, a MI of 1.1 g/10 minutes anda Vicat softening point of 126° C., 76.75% by weight of L-LDPE resin ofwhich α-olefin is 4-methylpentene-1 having a density of 0.920 g/cm³, 2.1g/10 minutes and a Vicat softening point of 100° C., 3% by weight ofcarbon black and 0.05% by weight of oleic acid amide 0.25% by weight ofantioxidant, and its thickness is 25 μm.

Example XII

The packaging material of Example XII corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene-vinyl acetate copolymer resin filmlayer composed of 59.7% by weight of EVA resin of which vinyl acetateunit content is 19% by weight (saponification method) having a MFR of2.5 g/10 minutes, a density of 0.94 g/cm³ and a Vicat softening point of64° C., 38% by weight of L-LDPE resin of which α-olefin is butene-1having a density of 0.890 g/cm³, a MI of 1 g/10 minutes and a Vicatsoftening point of 58° C. and 2% by weight of carbon black and 0.3% byweight of antioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example XI.

Example XIII

The packaging material of Example XIII corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene-vinyl acetate copolymer resin filmlayer composed of 59.7% by weight of EVA resin of which vinyl acetateunit content is 14% by weight (saponification method) having a MFR of1.4 g/10 minutes, a density of 0.93 g/cm³ and a Vicat softening point of70° C. 37% by weight of L-LDPE resin of which α-olefin is butene-1having a density of 0.906 g/cm³, a MI of 0.8 g/10 minutes and a Vicatsoftening point of 84° C. and 3% by weight of carbon black and 0.3% byweight of antioxidant, and its thickness is 25 μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example XI.

EXAMPLE XIV

The packaging material of Example XIV corresponds to embodiment of FIG.5.

The inner layer 1a is the ethylene-vinyl acetate copolymer resin filmlayer of which the resin composition is the same as the packagingmaterial of Example XII, and its thickness is 30 μm.

The thermoplastic resin film layer 2a is composed of 5% by weight ofLDPE resin having a density of 0.923 g/cm³, a MI of 2.4 g/10 minutes anda Vicat softening point of 92° C., 91.75% by weight of HDPE resin havinga density of 0.964 g/cm³, a MI of 0.4 g/10 minutes and a Vicat softeningpoint of 128° C. and 3% by weight of carbon black and 0.25% by weight ofantioxidant, and its thickness is 20 μm.

Example XV

The packaging material of Example XV corresponds to the embodiment ofFIG. 3.

The inner layer 1a is the ethylene-vinyl acetate copolymer resin filmlayer composed of 59.7% by weight of EVA resin of which vinyl acetateunit content is 19% by weight (saponification method) having a MFR of2.5 g/10 minutes, a density of 0.94 g/cm³ and a Vicat softening point of64° C., 38% by weight of L-LDPE resin of which α-olefin is4-methylpentene-1 having a density of 0.920 g/cm³, a MI of 2.1 g/10minutes and a Vicat softening point of 100° C. and 2% by weight ofcarbon black and 0.3% by weight of antioxidant, and its thickness is 25μm.

The thermoplastic resin film layer 2a is the same as the packagingmaterial of Example XI.

Comparative Example III

The packaging material of Comparative Example III is a coextruded doublelayer film composed of the layer having the same resin composition asthe ethylene vinyl acetate copolymer resin film layer of Example XIV anda thickness of 50 μm and the layer having the same resin composition asthe thermoplastic resin film layer of Example XIV and a thickness of 50μm.

In this specification, MFR was measured according to the followingmethod, unless specifically mentioned.

MFR (g/10 minutes); ASTM D-1238 Modified.

Various properties of the above packaging materials were measured, andthe results are summarized in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                     Invention           Comparative                                               XI  XII XIII                                                                              XIV XV  III                                      __________________________________________________________________________    Layer Composition                                                                              FIG. 2                                                                            FIG. 3                                                                            FIG. 3                                                                            FIG. 3                                                                            FIG. 3                                                                            --                                       Inner Layer Thickness (μm)                                                                  25 × 2                                                                      25 × 2                                                                      25 × 2                                                                      30 × 2                                                                      25 × 2                                                                      50                                       Outer Layer Thickness (μm)                                                                  25 × 2                                                                      25 × 2                                                                      25 × 2                                                                      20 × 2                                                                      25 × 2                                                                      50                                       Smoothness       B   B   B   B   B   D-E                                      Curling          A   A   A   A   A   D-E                                      Film Moldability B   B   B   B   B   D-E                                      Tear Strength MD (g)                                                                           >1600                                                                             >1600                                                                             >1600                                                                             723 >1600                                                                             205                                      Tear Strength CD (g)                                                                           >1600                                                                             >1600                                                                             >1600                                                                             >1600                                                                             >1600                                                                             >1600                                    Gelbo Test Strength (Times)                                                                     >300                                                                              >300                                                                              >300                                                                              >300                                                                              >300                                                                              >300                                    Slip Angle Reverse (degrees)                                                                    11  11  11  9   10  9                                       Slip Angle Right (degrees)                                                                      11  11  11  9    10                                                                              78                                       Impact Puncture Strength (kg · cm)                                                     >30                                                                               >30                                                                               >30                                                                              28   >30                                                                              21                                       __________________________________________________________________________

In Table 3, the evaluations and the testing methods are the same asthose in Table 2.

Examples In The Case Of L-LDPE Resin Film Layer And Light-reflectiveFlexible Sheet Layer Laminated Thereto Example XVI

The packaging material of Example XVI corresponds to the embodiment ofFIG. 9.

The L-LDPE resin film layer 1 and the thermoplastic resin film layer 2aare the same as Example I.

The light-reflective flexible sheet layer 6 consists of a biaxiallystretched nylon film 15 μm thick and an aluminum membrane layer 400 Åthick formed by vacuum metallizing. The light reflective flexible sheetlayer 6 is laminated so that the aluminum membrane layer is disposed onthe side of thermoplastic resin film layer 2a through the adhesive layer7 having a thickness of 15 μm consisting of LDPE resin having a MI of5.1 g/10 minutes and a density of 0.919 g/cm³ formed by extrusionlaminating.

Example XVII

The packaging material of Example XVII corresponds to the embodiment ofFIG. 10.

The L LDPE resin film layer 1a and the thermoplastic resin film layer 2aare the same as Example II.

The light-reflective flexible sheet layer 6 consists of a biaxiallystretched polyester film 12 μm thick and an aluminum membrane layer 400Å thick formed by metallizing. The light reflective flexible sheet layer6 is laminated so that aluminum membrane layer is disposed on the sideof thermoplastic resin film layer 2a through the same adhesive layer asemployed in Example XVI.

Example XVIII

The packaging material of Example XVIII corresponds to the embodiment ofFIG. 10.

The L-LDPE resin film layer 1a and the thermoplastic resin film layer 2aare the same as Example III.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVI.

Example XIX

The packaging material of Example XIX corresponds to the embodiment ofFIG. 10.

The L-LDPE resin film layer 1a and the thermoplastic resin film layer 2aare the same as Example IV.

The light-reflective flexible sheet layer 6 consists of a biaxiallystretched polypropylene resin film 20 μm thick and an aluminum membranelayer 400 Å thick formed by vacuum metallizing. The light-reflectiveflexible sheet layer 6 is laminated so that aluminum membrane layer isdisposed on the side of thermoplastic resin film layer 2a through thesame adhesive layer as employed in Example XVI.

Example XX

The packaging material of Example XX corresponds to the embodiment ofFIG. 10.

The L-LDPE resin film layer 1a and the thermoplastic resin film layer 2aare the same as Example V.

The light-reflective flexible sheet layer 6 consists of a diagonalunimolecular oriented HDPE resin film 35 μm thick having a density of0.964 g/cm³ and a MI of 0.4 g/10 minutes and an aluminum membrane layer400 Å thick formed by vacuum metallizing. The light-reflective flexiblesheet layer 6 is laminated so that aluminum membrane layer is disposedon the side of thermoplastic resin film layer 2a through the sameadhesive layer 7 as employed in Example XVI.

Comparative Example IV

The packaging material of Comparative Example IV is a coextruded doublelayer film composed of the layer having the same resin composition asthe ethylene-vinyl acetate copolymer resin film layer of Example XIX anda thickness of 50 μm and the layer having the same resin composition asthe thermoplastic resin film layer of Example XIX and a thickness of 50μm, and the same light-reflective flexible sheet layer 6 as Example XIXthrough the same adhesive layer 7 as employed in Example XIX.

Various properties of the above packaging material were measured, andthe results are summarized in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                     Invention                 Comparative                                         XVI  XVII XVIII                                                                              XIX  XX    IV                                 __________________________________________________________________________    Layer Composition                                                                              FIG. 9                                                                             FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                             --                                 Light-Reflective Layer                                                                         Al-Nylon                                                                           Al-Poly.                                                                           Al-Nylon                                                                           Al-PP                                                                              Al-HDPE                                                                             Al-PP                                                    ester                                                                    15 μm                                                                           12 μm                                                                           15 μm                                                                           20 μm                                                                           35 μm                                                                            20 μm                           Inner Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       30 × 2                                                                       25 × 2                                                                        50                                 Outer Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       20 × 2                                                                       25 × 2                                                                        50                                 Smoothness of Inflation Film                                                                   B    B    B    B    B     D-E                                Curling          A    A    A    A    A     C                                  Moldability of Inflation Film                                                                  B-C  B    B    B    B     D-E                                Tear Strength MD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              526  >1600 196                                Tear Strength CD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              >1600                                                                              >1600 >1600                              Gelbo Test Strength (Times)                                                                     >300                                                                               >300                                                                               >300                                                                               >300                                                                               >300  >300                              Impact Puncture Strength (kg · cm)                                                     >30  >30  >30  >30  >30    25                               __________________________________________________________________________

In Table 4, the evaluations and the testing methods are the same asTable 1.

Examples In The Case Of Ethylene-acrylate Ester Copolymer Resin FilmLayer And Light-reflective Flexible Sheet Layer Laminated TheretoExample XXI

The packaging material of Example XXI corresponds to the embodiment ofFIG. 9.

The ethylene-acrylate ester copolymer resin film layer 1 and thethermoplastic resin film layer 2a are the same as Example VI.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVI.

Example XXII

The packaging material of Example XXII corresponds to the embodiment ofFIG. 10.

The ethylene-acrylate ester copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example VII.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVII.

Example XXIII

The packaging material of Example XXIII corresponds to the embodiment ofFIG. 10.

The ethylene-acrylate ester copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example VIII.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVIII.

Example XXIV

The packaging material of Example XXIV corresponds to the embodiment ofFIG. 10.

The ethylene-acrylate ester copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example IX.

The light-reflective flexible sheet layer 6 and the adhesive layer arethe same as Example XIX.

Example XXV

The packaging material of Example XXV corresponds to the embodiment ofFIG. 10.

The ethylene-acrylate ester copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example X.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XX.

Comparative Example V

The packaging material of Comparative Example V is a coextruded doublelayer film composed of the layer having the same resin composition asthe ethylene-vinyl acetate copolymer resin film layer of Example XXIVand a thickness of 50 μm and the layer having the same resin compositionas the thermoplastic resin film layer of Example XXIV and a thickness of50 μm, and the same light-reflective flexible sheet layer 6 as ExampleXXIV through the same adhesive layer 7 as employed in Example XXIV.

Various properties of the above packaging material were measured, andthe results are summarized in Table 5.

                                      TABLE 5                                     __________________________________________________________________________                     Invention                 Comparative                                         XXI  XXII XXIII                                                                              XXIV XXV   V                                  __________________________________________________________________________    Layer Composition                                                                              FIG. 9                                                                             FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                             --                                 Light-Reflective Layer                                                                         Al-Nylon                                                                           Al-Poly.                                                                           Al-Nylon                                                                           Al-PP                                                                              Al-HDPE                                                                             Al-PP                                                    ester                                                                    15 μm                                                                           12 μm                                                                           15 μm                                                                           20 μm                                                                           35 μm                                                                            20 μm                           Inner Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       30 × 2                                                                       25 × 2                                                                        50                                 Outer Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       20 × 2                                                                       25 × 2                                                                        50                                 Smoothness of Inflation Film                                                                   B    B    B    B    B     C-D                                Curling          A    A    A    A    A     D-E                                Moldability of Inflation Film                                                                  B    B    B    B    B     C-D                                Tear Strength MD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              536  >1600 213                                Tear Strength CD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              >1600                                                                              >1600 >1600                              Gelbo Test Strength (Times)                                                                     >300                                                                               >300                                                                               >300                                                                               >300                                                                               >300  >300                              Impact Puncture Strength (kg · cm)                                                     >30  >30  >30   28  >30    21                               __________________________________________________________________________

In Table 5, the evaluations and the testing methods are the same asTable 1.

Examples In The Case Of Ethylene-vinyl Acetate Copolymer Resin FilmLayer And Light-reflective Flexible Sheet Layer Laminated TheretoExample XXVI

The packaging material of Example XXVI corresponds to the embodiment ofFIG. 9.

The ethylene-vinyl acetate copolymer resin film layer 1 and thethermoplastic resin film layer 2a are the same as Example XI.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVI.

Example XXVII

The packaging material of Example XXVII corresponds to the embodiment ofFIG. 10.

The ethylene-vinyl acetate copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example XII.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVII.

Example XXVIII

The packaging material of Example XXVIII corresponds to the embodimentof FIG. 10.

The ethylene-vinyl acetate copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example XIII.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XVIII.

Example XXIX

The packaging material of Example XXIX corresponds to the embodiment ofFIG. 10.

The ethylene-vinyl acetate copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example XIV.

The light-reflective flexible sheet layer 6 and the adhesive layer arethe same as Example XIX.

Example XXX

The packaging material of Example XXX corresponds to the embodiment ofFIG. 10.

The ethylene-vinyl acetate copolymer resin film layer 1a and thethermoplastic resin film layer 2a are the same as Example XV.

The light-reflective flexible sheet layer 6 and the adhesive layer 7 arethe same as Example XX.

Comparative Example V

The packaging material of Comparative Example V is a coextruded doublelayer film composed of the layer having the same resin composition asthe ethylene-vinyl acetate copolymer resin film layer of Example XXIXand a thickness of 50 μm and the layer having the same resin compositionas the thermoplastic resin film layer of Example XXIX and a thickness of50 μm, and the same light-reflective flexible sheet layer 6 as ExampleXXIX through the same adhesive layer 7 as employed in Example XXIX.

Various properties of the above packaging material were measured, andthe results are summarized in Table 6.

                                      TABLE 6                                     __________________________________________________________________________                     Invention                 Comparative                                         XXVI XXVII                                                                              XXVIII                                                                             XXIX XXX   VI                                 __________________________________________________________________________    Layer Composition                                                                              FIG. 9                                                                             FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                            FIG. 10                                                                             --                                 Light-Reflective Layer                                                                         Al-Nylon                                                                           Al-Poly.                                                                           Al-Nylon                                                                           Al-PP                                                                              Al-HDPE                                                                             Al-PP                                                    ester                                                                    15 μm                                                                           12 μm                                                                           15 μm                                                                           20 μm                                                                           35 μm                                                                            20 μm                           Inner Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       30 × 2                                                                       25 × 2                                                                        50                                 Outer Layer Thickness (μm)                                                                  25 × 2                                                                       25 × 2                                                                       25 × 2                                                                       20 × 2                                                                       25 × 2                                                                        50                                 Smoothness of Inflation Film                                                                   B    B    B    B    B     D-E                                Curling          A    A    A    A    A     D-E                                Moldability of Inflation Film                                                                  B    B    B    B    B     D-E                                Tear Strength MD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              673  >1600 233                                Tear Strength CD (g)                                                                           >1600                                                                              >1600                                                                              >1600                                                                              >1600                                                                              >1600 >1600                              Gelbo Test Strength (Times)                                                                     >300                                                                               >300                                                                               >300                                                                               >300                                                                               >300  >300                              Impact Puncture Strength (kg · cm)                                                     >30  >30  >30  >30  >30    23                               __________________________________________________________________________

In Table 6, the evaluations and the testing methods are the same asTable 1.

We claim:
 1. A packaging material which comprises a pair of coextrudedmultilayer inflation film layer disposed symmetrically and joinedthrough a pseudo-adhesive portion formed by blocking thereof whereinsaid multilayer inflation film layer comprises a linear low densitypolyethylene resin film layer containing more than 50% by weight oflinear low density polyethylene resin having a density of less than0.925 g/cm³ and 0.01 to 2% by weight of an antioxidant disposed on theinside joined through a pseudo-adhesive portion formed by blocking and athermoplastic resin film layer containing a substance havingantiblocking activity disposed on the outside.
 2. The packaging materialof claim 1 wherein the Vicat softening point of said linear low densitypolyethylene resin is lower than 110° C.
 3. A packaging material whichcomprises a pair of coextruded multilayer inflation film layers disposedsymmetrically and joined through a pseudo-adhesive portion formed byblocking thereof wherein the inside layer of said multilayer inflationfilm layer joined through said pseudo-adhesive portion is anethylene-acrylate ester copolymer resin film layer.
 4. A packagingmaterial which comprises a pair of coextruded multilayer inflation filmlayers disposed symmetrically and joined through a pseudo-adhesiveportion formed by blocking thereof wherein said multilayer inflationfilm layer comprises an ethylene-acrylate ester copolymer resin filmlayer containing more than 50% by weight of an ethylene-acrylate estercopolymer resin of which the content of methylacrylate unit,ethylacrylate unit or a mixture thereof is more than 7% by weight and0.01 to 2% by weight of an antioxidant disposed on the inside joinedthrough a pseudo-adhesive portion formed by blocking and a thermoplasticresin film layer containing a substance having antiblocking activitydisposed on the outside.
 5. A packaging material which comprises a pairof coextruded multilayer inflation film layers disposed symmetricallyand joined through a pseudo-adhesive portion formed by blocking thereofwherein the inside layer of said multilayer inflation film layer joinedthrough said pseudo-adhesive portion is an ethylene-vinyl acetatecopolymer resin film layer.
 6. The packaging material of claim 1, claim3 or claim 5 which further contains a light-reflective flexible sheetlayer.
 7. A packaging material which comprises a pair of coextrudedmultilayer inflation film layers disposed symmetrically and joinedthrough a pseudo-adhesive portion formed by blocking thereof whereinsaid multilayer inflation film layer comprises an ethylene-vinyl acetatecopolymer resin film layer containing more than 35% by weight ofethylene-vinyl acetate copolymer resin of which the content of vinylacetate unit is more than 5% by weight disposed on the inside joinedthrough a pseudo-adhesive portion formed by blocking and a thermoplasticresin film layer containing a substance having antiblocking activitydisposed on the outside.
 8. A packaging material which comprises a pairof coextruded multilayer inflation film layers disposed symmetricallyand joined through a pseudo-adhesive portion formed by blocking thereofwherein the outer layer of said multilayer inflation film layer disposedon the outside of the pair of the multilayer inflation film layers is aheat-sealable thermoplastic resin film layer containing more than 10% byweight of an ethylene copolymer resin, a light-shielding material and alubricant.
 9. The packaging material of claim 8 wherein saidthermoplastic resin film layer has a Vicat softening point higher thanthe inner layer by 5° C. or more.
 10. The packaging material of claim 8wherein said thermoplastic resin film layer has a slip angle of 6 to 60degrees.
 11. The packaging material of claim 8 wherein saidthermoplastic resin film layer contains a substance having antiblockingactivity.
 12. The packaging material of claim 11 wherein said substancehaving antiblocking activity is a member selected from the groupconsisting of silica, diatomaceous earth, talc, calcium silicate,aluminum silicate, magnesium, silicate, calcium carbonate, polyvinylesters of higher fatter acid, n-octadecylurea dicarboxylic acid esteramides, N,N',-dioleylhydroxyamido, and lubricants and light-shieldingmaterials having antiblocking activity.
 13. The packaging material ofclaim 11 wherein said substance having antiblocking activity is a memberselected from the group consisting of carbon black, fatty acid amides,silica, talc, calcium carbonate, metal powder and titanium dioxide. 14.The packaging material of claim 6 wherein said light-reflective flexiblesheet layer is a metallized flexible sheet layer.
 15. The packagingmaterial of claim 11 wherein said substance having antiblocking activityis more than 0.5% by weight of polyethylene resin having a density ofmore than 0.940 g/cm.